ARP modules (was: OTA question)

Joachim Verghese jocke at
Mon Oct 16 08:44:24 CET 1995

On Fri, 13 Oct 1995, Don Tillman wrote:

> I have no idea what's inside the Odyssey module, so now I'm incredibly
> curious; what's the circuit like?  How on earth do they use an LM3900
> in a VCF circuit?

Basically, there are four similar stages, each consisiting of a
dual PNP (apparently matched 3906s) gain stage which feeds a 3900
amp connected as a (Miller) integrator.

> How did you get a schematic?

Reverse engineering. In fact, I've got schematics of some other modules
as well (incl. the 4034/4035 4-pole ladder filter), and I've been
planning to put them in my WWW pages when I have time.


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